SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c69d9f79629e29d63b9d8f399d4eb6c0d33b4cddb4e9e6a8c3ea643c38413d3' 
  AND token = 'VYUu8ieTiL1SLp+jPZZ/Vt5OeHvE5n/vGBh0SJ2pBfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}